Technically it should be easy to improve on the iPad if you are going just by specifications, but it's a complete package of gadget, os, ui, software and appstore. Beating that combination is going to be the difficulty. Especially after the iOS upgrade this fall.
I suspect we have been conditioned by computers for so long we expect the iPad to behave like our desktops.
It's easy to fit a camera, but then I never used the one on my main machine. USB is again an easy upgrade but I can live happily without it. Flash is turned off on my main machine and I never miss it, so why bother? More ram would be nice and a faster cpu but not at the expense of battery life.
What I definately don't want is a slow unresponsive machine which runs bloated software.
Still it's new, it's evolving and I'm looking forward to alternative implementations of the format. Apple's not perfect and a good kick in the pants can only be beneficial in the long run